Liquid crystal materials can be applied to optical films such as polarizing plates and wave plates for use in flat panel display devices (FPD). As such a liquid crystal material, a polymerizable liquid crystal compound, which brings about a higher-order smectic liquid crystal phase including a cycloalkane-derived structure, has been the focus on attention.
Meanwhile, in order to make the polymerizable liquid crystal compound (including a composition containing the liquid crystal compound) into an optical film, it is necessary to (i) apply the polymerizable liquid crystal compound to a base material and dry the polymerizable liquid crystal compound and then (ii) polymerize the liquid crystal compound at a temperature which falls within a range of temperatures at which a higher-order smectic liquid crystal phase is exhibited and which is equal to or more than a crystal transition temperature. In theory, a defect-free, homogeneous optical film can be obtained by polymerizing the liquid crystal compound at a temperature satisfying the above temperature conditions. In a case where the liquid crystal compound is polymerized with the use of a photopolymerization initiator, however, there exist heat including (i) heat generated by a light source and (ii) heat of polymerization. Therefore, it is extremely difficult to control a temperature during polymerization so that the temperature falls within a desired range. In practice, therefore, it is necessary to polymerize the polymerizable liquid crystal compound at a temperature around room temperature. That is, the polymerizable liquid crystal compound needs to be a compound which brings about a non-crystallizable, higher-order smectic liquid crystal phase at a temperature around room temperature.